CODEWITHSUNDEEP
asn.1nssrfc3161
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Reputation: 988

How to model the RFC3161 Accuracy ASN.1 SEQUENCE using NSS's SEC_ASN1Template?

The ASN.1 definition of Accuracy is:

Accuracy ::= SEQUENCE {
    seconds     INTEGER          OPTIONAL,
    millis  [0] INTEGER (1..999) OPTIONAL,
    micros  [1] INTEGER (1..999) OPTIONAL  }

What is unclear to me is how to handle millis and micros. It can't work to have both the SEC_ASN1_INTEGER universal tag and the 0 and 1 tags in the same 'kind' field of a SEC_ASN1Template struct, as they both would go into the same part (the lowest byte) of that field.

Upvotes: 0

Views: 136

Answers (1)

jsantander
jsantander

Reputation: 5102

Note that

millis [0] INTEGER (1..999) OPTIONAL

is not really of INTEGER type, but of [0] type.

Perhaps the following equivalent type definition might help you:

Accuracy ::= SEQUENCE {
    seconds     AccuracySeconds      OPTIONAL,
    millis  [0] AccuracyMilliseconds OPTIONAL,
    micros  [1] AccuracyMicroseconds OPTIONAL  }

AccuracySeconds ::= INTEGER
AccuracyMilliseconds ::= INTEGER(1..999)
AccuracyMicroseconds ::= INTEGER(1..999)

Also need to take into account if your type definition is using IMPLICIT tagging or EXPLICIT tagging... encoding would be different:

(implicit) 

30 06
   01 01 02
   80 01 02

vs (explicit)

30 08
   01 01 02
   A0 03
      02 01 02

Upvotes: 1

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